Help with a blend

Well, seeing as you're all so wonderful with these things I was wondering if anyone could help me? I use Photoshop 6 and I was wondering if any of you have any clue on how to get rid of those lines that appear after you blend a couple pictures.


If you look at the top right corner you can see the edges of the picture. You can tell it was a square screencap. How do you get rid of that?

Massi